1. Field of the Invention
The present invention relates to an elevator control device using an electric power storing unit.
2. Description of the Related Art
An example of an elevator control device is shown in FIG. 10. FIG. 10 is a block diagram showing the structure of a conventional elevator control device.
Referring to FIG. 10, reference numeral 1 denotes a commercial three-phase a.c. power supply (hereinafter, referred to as xe2x80x9ccommercial power supplyxe2x80x9d), and 2 is an electric motor such as an induction motor. Reference numeral 3 denotes a winding machine which is connected to the electric power 2. Reference numeral 4 denotes a rope which is disposed on the winding machine 3. Reference numeral 5 denotes an elevator cage which is disposed on one end of the rope 4. Reference numeral 6 denotes a balance weight which is disposed on the other end of the rope 4.
The electric motor 2 is driven by the power supply from the commercial power supply 1, and the winding machine 3 is rotationally driven by driving the electric motor 2. Then, the rope 4 disposed around the winding machine 3 makes the elevator cage 5 and the balance weight 6 which are connected to each end of the rope 4, respectively, move so that a passenger within the cage 5 is carried to a desired floor.
Reference numeral 7 denotes a convertor which is made up of a diode or the like. The convertor 7 which is connected to the commercial power supply 1 rectifies an a.c. power supplied from the commercial power supply 1 so as to convert the a.c. power into a d.c.power. Reference numeral 8 denotes an inverter which is made up of transistors, IGBTs and so on. Reference numeral 8 denotes an inverter which converts the d.c. power converted by the convertor 7 into an a.c. power having a variable voltage and a variable frequency. Reference numeral 9 denotes a regenerative resistor. Reference numeral 10 denotes a regenerative resistor control circuit which is connected in series to the regenerative resistor 9. The regenerative resistor 9 and the regenerative resistor control circuit 10 are disposed between the convertor 7 and the inverter 8.
Reference numeral 11 denotes a controller which decides the start/stop of the elevator and also produces a position/velocity command that commands the position and velocity of the elevator. Reference numeral 12 denotes a current detecting unit which is disposed between the electric motor 2 and the inverter 8. Reference numeral 13 denotes an encoder which is mounted on the winding machine 3. Reference numeral 14 denotes an inverter control circuit which allows the electric motor 2 to be rotationally driven by current feedback from the current detecting device 12 and speed feedback from the encoder 13 which are based on the position/velocity command from the controller 11, to thereby realize the position/velocity control of the elevator. Reference numeral 15 denotes a gate drive circuit that controls an output voltage and a frequency which are outputted from the inverter 8 on the basis of a signal from the inverter control circuit 14 to control the electric motor 2 and the elevator.
The balance weight 6 of the elevator is balanced with the cage 5 when an appropriate number of persons are in the cage 5. For example, in the case where the elevator travels and the balance weight 6 is balanced with the weight of the entire cage 5 including the passengers, although electric power is consumed at the time of acceleration, a kinetic energy can be returned to the electric power supply during deceleration. However, in a general elevator, the electric power obtained from the kinetic energy during deceleration is converted into thermal energy by the regenerative resistor 9 due to on/off switching of the regenerative resistor control circuit 10, thus being consumed.
As described, in the conventional elevator control device, unless the electric power is supplied from the commercial power supply 1, the elevator cannot be operated.
The present invention has been made in order to solve the above problem, and therefore an object of the present invention is to provide an elevator control device suppressing power supplied from a commercial power supply by using regenerative electric power from kinetic energy from regenerative operation when an elevator is decelerated.
In order to achieve the above object, according to the present invention, there is provided an elevator control device, comprising: a convertor which rectifies an a.c. power and converts the a.c. power into a d.c. power; an inverter which converts the d.c. power into an a.c. power having a variable voltage and a variable frequency; an electric motor which is driven by the a.c. power having a variable voltage and a variable frequency to drive an elevator; a power storing unit which is charged with an electric power; a required-power arithmetically operating circuit which calculates a required power of the elevator which is an electric power required for the operation of the elevator or an electric power caused by the operation of the elevator; and a charging/discharging control circuit which controls the charging operation or the discharging operation of the power storing unit based on the required power of the elevator.
Also, according to the present invention, there is provided the elevator control device further comprising a required-power arithmetically operating unit which calculates the required power of the elevator and outputs an obtained required-power value to a charging/discharging control unit through communication means.
Further, according to the present invention, there is provided the elevator control device in which the charging/discharging control circuit controls so that the electric power is charged in the power storing unit when a required power of the elevator is a negative value and an electric power occurs due to the operation of the elevator, and the electric power is discharged from the power storing unit when a required power of the elevator is a positive value and the electric power is required for the operation of the elevator.
Still further, according to the present invention, there is provided the elevator control device in which the charging/discharging control circuit controls so that the electric power is charged in the power storing unit from the commercial power supply when the required power of the elevator is 0 and the elevator stops.
Yet still further, according to the present invention, there is provided the elevator control device further comprising a charging/discharging circuit which conducts the charging operation or the discharging operation of the power storing unit under the control of the charging/discharging control circuit, wherein the charging/discharging control circuit controls the electric power discharged from the power storing unit on the basis of the required power of the elevator when the electric power of the elevator is a positive value and the electric power is required for the operation of the elevator, and controls an output voltage from the charging/discharging circuit to the power storing unit to a given voltage when the required power of the elevator is a negative value and the electric power occurs due to the operation of the elevator.
Yet still further, according to the present invention, there is provided the elevator control device in which the output voltage controlled to the given voltage which is outputted from the charging/discharging circuit is set to be higher than the voltage value obtained by rectifying the supply voltage.
Yet still further, according to the present invention, there is provided the elevator control device in which the charging/discharging control circuit controls so that the electric power is discharged from the power storing unit by an excessive electric power amount which exceeds a given electric power amount on the basis of the required power of the elevator.
Yet still further, according to the present invention, there is provided the elevator control device in which the charging/discharging control circuit controls the electric power amount discharged from the power storing unit on the basis of a predetermined time zone.
Yet still further, according to the present invention, there is provided the elevator control device in which the charging/discharging control circuit switches between a case in which only an excessive electric power amount which exceeds the predetermined electric power amount with respect to the required power of the elevator is discharged from the power storing unit, and a case in which the given electric power amount is stably discharged from the power storing unit.
Yet still further, according to the present invention, there is provided the elevator control device in which the required-power arithmetically operating circuit calculates the required power of the elevator on the basis of a voltage command value for applying the voltage to the electric power and an electric motor current or a current command value for supplying a current to the electric motor.